Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the safety profile is covered. The description adds genuinely new behavioral context: the data is a point-in-time snapshot (potentially stale) and the tool does not perform verification, warning the agent not to treat the output as authoritative. It does not say where the snapshot comes from or how it is selected.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short sentences, front-loaded with the resource and its returned contents, then a single scoping caveat. Dense but no wasted sentences; "evidence limitations" is slightly opaque but earns its place as a returned-field label.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description usefully enumerates the returned fields, which compensates well. But a zero-parameter tool reading "snapshot" provenance raises an unexplained question: which snapshot is read (global/current only)? That scoping gap plus the absence of output structure leaves an agent guessing about the response shape.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool has zero parameters, so there is nothing the description needs to explain at the parameter level. Baseline of 4 applies; no parameter claims are made or contradicted.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (read) and resource (snapshot provenance) and enumerates exactly what is returned: snapshot dates, pinned upstream commit, source hashes, license, counts, evidence limitations. It does not name the sibling tools or differentiate itself from read_document_metadata, so it stops short of a 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The second sentence gives a useful negative boundary ("not a live monitor or independent verification"), which implies when to avoid it. However, it never says when to prefer it over read_document_metadata or search_document_metadata, leaving the positive selection criteria to inference.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.